Method for producing high tenacity artificial yarn and cord



Sept. 30, 1952 H. D. MERION ET AL 2,611,928

METHOD FOR PRODUCING HIGH TENACITY ARTIFICIAL YARN AND CORD Filed Nov. 23, 1948 INVENTORS HOWARD D. ME/P/ON f/ENE) J McDERMOTT Patented Sept. 30, 1 952 METHOD FOR PRODUCING HIGH TENACITY ARTIFICIAL .YARN GORD Howard D. Marion, West Chester, and 'Henry ".L

Mc'Dermo'tt,"Collingdale, Pa., ass'ignors to American Viscose Corporation, 'Wilmington, Del, a

corporation -of Delaware Application November 23, 1948, SeriaLNorBLS iZ -'Claims. 1

This invention relates 'to'the production-of high tenacity artificial filamentary yarns and cord from regenerated cellulose by the viscose process, and has as its object animproved process adapted to produce yarns and cords having increased flexing life.

.In accordance with the present invention, it has beenfound that improved regenerated cellulose yarns and cords having high tenacity and long flexing life can be obtained by spinning a viscose having a temperature of at least 30 G. into a regenerating coagulating bath having a temperature of 40 to 7.5 C. or higher, stretching the partially regenerated filaments between 40 and 80%, washing out the acid while completing the regeneration of the filaments, relaxing, drying. and collecting by winding and/or twisting.

The viscose to bespun proceeds from the ripening and filtering equipment which is usually disposed in a separate room, commonly in a basemerit where a low room temperature from '18 to 22 C. may .be maintained. As such viscose proceeds through the lines to the spinning machine in the spinning rooms, it may absorb some heat and rise to a temperature of 25 to 28 C. by the time it reaches the spinnerets of the machine. In order to raise the temperature into the .range of at least 30 0., means is provided for heating a portion of the line through which the viscose passes on its way to the spinnerets. While the heating means could be applied to a common system for feeding a number of machines in the spinning room, or to the header associated with each spinning machine, it is preferred for reasons statedhereinafter to provide a system of heating the individual supply lines leading to the spinnerets. "For example, electric heating coils, high frequency electrostatic heating devices, or heating baths maybe applied to the viscose lines; The individual supply line or rounder may comprise a tortuous channel made by bending a portion of its length into the form of a helical coil, and this rounder may be submerged in the spinning bath to. derive its heat from such bath or it may be'submerged'in some other liquid bath having a, sufiiciently high temperature to heat the viscose to the proper temperature; When a hot aqueous liquid (at 60 to 100 0.) is used for treating the yarns before, after, or during stretching, the hot liquid can be circulated through the yarn-treating stage and the viscoseheating stage in succession .in either order.

It has been found that it is necessary not only to have the viscose at a proper temperature but also to relax the filaments in an amcunt of the order of 3 to 10% after stretching and 'before or during drying in .order to obtain. a combina-- tion of a high tenacity and exceptionally/long flexing life.

Before drying the ,yarn and after 'it has been rendered acid-free, asoft 'finishmay be obtained by the application of sodium oleate, polyvinyl alcohol, ethylene oxide, modified sorbitan' dipalmitate, or compositions containingsuchi'ingradients insuitable proportions. If .desired,fdesulfurization, bleaching, and such procedures may be applied with appropriateintermediate Such treatments should. precedethe washes. application of a softener when such softener desired .to be applied to the product. Depending upon the use to which theyarn obtained "isflhftended to be put, it may be collected with or without twist. When it is desired to producejtire cord from such yarn, it 'is generally preferred to collect the individual yarns with a predetermined amount of twist so that a subsequent doubling operation may serve to combine the desired number of individual plies in the final cord with the proper twist in the plies and the cord respectively. v V

In the following-examples, 'the relative fatigue rating .or;fiexing life is determined on the flexing machine of the U. S. Rubber Company, in'which a number-of the cords are assembled in parallel relationship into a ribbon or band'30 inches long and the ribbon thusobtained is secured at. the opposite end within two Jews, the upper or which is reciprocated :inch from the initial setting with the bands taut at a frequency of sooner minute. A tension .device on the lower jaw'takes up any slack developedbecauselof permanent elongation during the test. This flexing is carried out at a temperature of about 120 The viscose employed may have from 6 to;8% cellulose, (which may be wood, cotton, linters,.=or any mixture thereof, preferably from :50 Ito 100% cotton) 6 to 8% caustic, and 30 to.-40% carbon disulfide based on the cellulosein the viscose; The salt test may be from 3 to 6 and the ball fall viscosity before heating may be from 40 to 200 seconds. 3 i The spinning bath may 'contain'from '7 to 12% sulfuric-acid, 15 to 25% sodium'sulfate, and from 1 to 10% of the sulfate of 'zinc,'magnesium,'or iron, or a mixture r the latter sulfates. The viscose preferably should havea tempera;- ture of 45 C. to C, 'andthe bath'a tempera-'- 'ture of 50 to c.- In thepre'ferred instance the. difference in temperature between theiivisl- 3 cose and spirming bath is not over 10 C. and the optimum difference is about C. to C.

The drawing illustrates a preferred embodiment of equipment in accordance with the present invention. As shown, the single figure represents a schematic view in perspective with parts in section.

As shown, the viscose is fed to the machine through a header 3 to which there are connected a number of branch outlets 4 connected to the individual spinning pumps 5 of positive displacement type, such as ordinary gear pumps. The discharge lines 6 from the individual pump 5 lead to a candle filter 1 through a swivel joint la which allows swinging of the candle filter 1 and rounder 8 in a counterclockwise direction as viewed in the figure, to remove the spinneret 9 out of the coagulating bath contained within the receptacle I0, which may be a trough extending the length of the machine or individual recep- I tacles, one for each spinneret. A feed pipe H serves to supply the coagulating bath to the receptacle l0 and an overflow pipe l2 displaced from H longitudinally of the machine serves to control the level of the bath in the trough i0 and assures circulation of the bath past the spinneret or spinnerets 9.

A receptacle I3 is provided alongside receptacle l0 and may be insulated therefrom by a layer 14 of material of low heat-conductivity. Like 40, the receptacle I3 may be individual for each rounder or it may be a trough running the length of the machine. An overflow pipe 15 is provided for controlling the level of heated liquid in the container I3. The rounder 8 is formed with a portion Ba thereof in the form of a helical coil to provide for heat transfer from the bath in container I3 to the viscose in the rounder 8 before it is fed to the spinneret 9.

Filaments passing from the coagulating bath in the receptacle i0 proceed upwardly to a thread-advancing device which may comprise a pair of canted rotors l6 and I! about which a predetermined number of wraps of the yarn are Wound to provide further regeneration prior to stretching. The yarn leaves the upper rotor 16 and passes through container 18 for a hot aqueous liquid continuously supplied thereto from a pipe 19. The aqueous medium may be hot water, hot dilute acids or salts, and may for example contain from 1 to 5% sulfuric acid, 1 to 3% sodium sulfate, and to 1 of zinc sulfate. As shown, the overflow-pipe 26 in the container i8 discharges into the container '13 for heating the viscose in the tortuous channel 8a. A threadadvancing reel or equivalent thread-advancing device 2| rotates at a peripheral speed from to 80% higher than the peripheral speed of rotors i6 and IT, to provide the stretch needed at this stage. On the reel 2|, a washing liquid, such as cold or hot water, cold or hot dilute acid or salt solutions, such as a solution containing from 0.1 .to 0.5% sulfuric acid, is supplied from a spray or shower head 22, and additional wash water may be sprayed on the reel by spraying head 22a, and the yarn departing from reel 2! passes under a pulley or rotor 23 immersed in a bath of a soft finish in a container 24 and then it proceeds around a thread-advancing device for drying comprising a pair of rotors 25 and 26 which are driven at a peripheral speed at the yarn-receiving portion somewhat less than the peripheral speed of discharge from reel 2!. The surfaces of the rotors 25 and 26 may have intermediate tapered portions 21 and 28 respectively to allow further shrinkage of the thread during the drying as it reaches this portion of the device. This taper may amount to 3 to 10%. If all of the shrinkage is carried out on the tapered portion of the rotors 25 and 26, their peripheral speed at the yarn-receiving end may be the same as the peripheral speed of the reel 2| and all shrinkage may be performed on the drums. On the other hand, the differential in the speed between the drums 25, 26 and reel 2| may be suflicient to take care of all the shrinkage desired, in which case the drums 25 and 26 may be cylindrical throughout their length. Generally, it is preferred to have a portion of the shrinkage occur before the drying drums 25 and 25 are reached, and a portion of the shrinkage occurs on an intermediate portion of the dryer drum where the moisture content has been reduced to about 150% based on the weight of the yarn.

After the yarn departs from the drums or otherwise heated rollers 25 and 25, it is collected by winding or by winding and twisting at 29.

Example I A viscos containing 7.8% cellulose, 6.6% caustic, 36% carbon disulfide (CS2 based on the alpha cellulose content of the pulp) and having a salt point of 5 as determined with sodium chloride was spun into a bath containing 10% sulfuric acid, 4.5% zinc sulfate and 21 sodium sulfate at 50 C. to produce a 1650 denier, 980 filament yarn. The rounder comprised a 7-foot long stainless steel helical coil immersed in hot water at 60 C. The viscose was heated to 45 C. and the immersion travel of the filaments in the bath was 12 inches at a spinning speed of 107 meters per minute. A 16-yard storage was used on the rotors l6 and ll of the drawing and immediately thereafter the yarn was stretched 65%. Hot water at about C. was used in trough 18. After washing to a neutral condition, the yarn passed through a soft finish and was allowed to relax a total of 8%, about 5% on the way to the drying stage and about 3% on a tapered portion of the drying drums. The yarn produced had a dry tenacity of 3.63 grams per denier, a dry elongation of 11.9%, a wet tenacity of 2.28 grams per denier,'a wet elongation of 22.0% and a fatigue rating of 135.

The same viscose spun into the same bath and under the same conditions, except that the viscose was not heated but had a temperature of 27 C. as it issued from the spinneret, yielded a yarn having adry tenacity of 3.65 grams per denier, a dry elongation of 10.8%, a wet tenacity of 2.21 grams per denier, a wet elongation of 20.7, and a fatigue rating of 114. When this same procedure is carried out without relaxation and without heating of the viscose, a fatigue rating of 47 to 60 is generally obtained.

Example II Viscose was spun under the same conditions as in Example I and was heated to a temperature of 45 0., except that the storage on the rotors l6 and I? was reduced to 2 yards. The resulting yarn had a dry tenacity of 3.43 grams per denier, a dry elongation of 12.8%. a wet tenacity of 2.21, a wet elongation of 20.5, and a fatigue rating of 180. This shows the great improvement obtainable by stretching filaments in a less completely regenerated condition.

The following table lists additional examples using the same conditions as Example II except the shrinkage or relaxation on the way to the drying stage was reduced to 4% and the temperaturewas varied as indicated.

which the filaments are stretched approximately 65%.

A comparison of the results shown in the pre:

ceding illustrative examples shows the excep-J tionally good flexing life and how this has been increased by the present invention without any sacrifice in the tenacity of the yarn. In general; it has been found that the heating of the viscose just before spinning gets rid of so-called native cellulose, so that a more uniform filament is ob tained. i Apparently this reduction or complete elimination of native cellulose renders the substance of the filament more amenable to the subsequent processes of stretching and relaxation so that the final product has remarkably improved fiexing life without any decrease in tenacity. The reason for such improvement is not clearly understood, but it is clear that stretching should be performed on the filaments while still undergoing regeneration, and preferably before the regeneration has been A; to A; completed.

The product of the present invention can be used for the production of filament yarns or staple fiber yarns where high tenacity regenerated cellulose filaments or fibers are desired. It is pai} ticularly advantageous in the production of cords used for reinforcing rubber goods, such as tires, belts, and the like.

It is to be understood that changes and variations may be made Without departing from the spirit and scope of the present invention, as defined in the appended claims.

We claim:

1. A process of producing high tenacity regenerated cellulose filaments having a long flex-life comprising the steps of extruding viscose having a temperature of 30 C. to about 70 C. into an acid regenerating and coagulating bath having a temperature of at least 40 C., stretching the filaments 40 to 80% after partial regeneration but before complete regeneration, washing the filaments and completing the regeneration, relaxing the filaments 3 to and drying them.

2. The process of claim 1 in which the temperatures of the viscose and bath are no more than 10 C. apart.

3. The process of claim 1 in which the temperatures of the viscose and bath are no more than 5 C. apart.

4. The process of claim 1 in which part of the relaxation is effected immediately before drying and the remainder during drying.

5. A process in accordance with claim 1 in which the filaments are subjected to a hot aqueous liquid having a temperatureof 60 C. to 100 C. during stretching.

6. A process in accordance with claim 5 in 7. A process in accordance with claim 5 in which the hot aqueous liquid is applied to heat the viscose passing to the *spinneret.

-8. A process of producing high tenacity regenerated cellulose filaments having a long flexlife comprising the steps 'of extruding viscose having a temperature of 45 to 60 C. into an acid regenerating and coagulating bath having a. temperature of 40 to 75 cgsftretching the filaments 40 to 80% after partial regeneration but before complete regeneration, washing the filaments and completing the regeneration, relaxing the filaments 3 to 10 and drying them.

9. A process of producing high tenacity regenerated cellulose filaments having a long flex-life comprising the steps of extruding viscose having a temperature of 30 C. to about C. into an acid regenerating and coagulating bath having a temperature of at least 40 0., stretching the filaments 40 to 80 after partial regeneration but beforeregeneration is half completed, washing the filaments and completing the regeneration, relaxing the filamentsB to 10%, and drying them.

10. A process of producing high tenacity regenerated cellulose filaments having a long flexlife comprising the steps of extruding viscose having a temperatureof45 to 60 C. into an acid regenerating and coagulating bath having a temperature of 40 to CL, stretching the filaments 40 to after partial regeneration but before regeneration is half completed, washing the filaments and completing the regeneration, relaxirm the filaments 3 to 10 and drying them.

HOWARD D. MERION. HENRY J. MCDERMOTT.

REFERENCES orrnn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,293,825 Hosfield Aug. 25, 1942 2,348,415 Polak May 9. 1944 2,413,123 Underwood Dec. 24, 1946 2,427,993 McLellan Sept. 23, 1947 2,433,783 Brown 1 Dec. 30, 1947 FOREIGN PATENTS Number Country Date 345,938 Great Britain Mar. 30, 1931 

1. A PROCESS OF PRODUCING HIGH TENACITY REGENERATED CELLULOSE FILAMENTS HAVING ALONG FLEX-LIFE COMPRISING THE STEPS OF EXTRUDING VISCOSE HAVING A TEMPERATURE OF 30* C. TO ABOUT 70* C. INTO AN ACID REGENERATING AND COAGULATING BATH HAVING A TEMPERATURE OF AT LEAST 40* C., STRETCHING THE FILAMENTS 40 TO 80% AFTER PARTIAL REGENERATION BUT BEFORE COMPLETE REGENERATION, WASHING THE FILAMENTS AND COMPLETING THE REGENERATION, RELAXING THE FILAMENTS 3 TO 10%, AND DRYING THEM. 